Nature of Dielectric Relaxation in Microcrystalline Cellulose

Alekseev, О. М.; Str., Volodymyrska; Kovalov, Kostiantyn M.; Lazarenko, M. M.; Lazarenko, M. V.; Grabovskii, Yurii E.; Tkachov, Sergii Yu.

doi:10.35812/cellulosechemtechnol.2019.53.02

Cited by 16 publications

(5 citation statements)

References 12 publications

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“…, , tg and R were measured at four frequencies f5, 10, 20, 50 kHz, within the temperature range of 50-50C. An automated setup based on the alternating-current bridge P5083 was used [20].…”

Section: Methodsmentioning

confidence: 99%

Configuration Transformations in Polyvinyl Chloride–Methylene Blue Composites

2022

Nanosistemi, Nanomateriali, Nanotehnologii

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Bulk samples of pure polyvinyl chloride (PVC) and its composites with different content of methylene blue (MB) dye are prepared. The degree of crystallinity, dynamic elastic modulus E and shear modulus G (1 MHz), photoluminescence (PL), temperature dependences of dielectric characteristics  1 ,  2 , tg, electrical resistance R at different frequencies of alternating electric field are measured. As shown, the adding of a modifier (MB) with conjugated chromophores is accompanied by both the generation of linear conjugated systems (polyenes) in PVC and the destruction of monomer units. These processes are mechanisms for changing the mechanical, structural, optical, dielectric properties of PVC-MB composites caused by the peculiarities of the stack interaction between their conjugated components.Виготовлено об'ємні зразки чистого полівінілхлориду (ПВХ) і його композитів з різним вмістом барвника метиленового синього (МС). Проведено міряння ступеня кристалічности, динамічних модулів пружности Е і зсуву G (1 МГц), фотолюмінесценції (ФЛ), температурних залежностей діелектричних характеристик  1 ,  2 , tg, електроопору R за різних частот змінного електричного поля. Показано, що внесення модифікатора (МС) із спряженими хромофорами супроводжується ґенерацією у ПВХ лінійних спряжених систем (полієнів) і деструкцією мономерних ланок. Вказані процеси є механізмами зміни механічних, структурних, оптичних, діелектричних властивостей композитів ПВХ-МС, викликаних особливостями стекової взаємодії між їхніми спряженими компонентами.

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Section: Methodsmentioning

confidence: 99%

Configuration Transformations in Polyvinyl Chloride–Methylene Blue Composites

2022

Nanosistemi, Nanomateriali, Nanotehnologii

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“…Based on this line of reasoning, we can treat the nanocrystal with thermally activated motion as a two-state system that can relax (a “two-level relaxator”). The change in the dielectric permittivity of the system, i.e., the difference between the static dielectric permittivity and the dielectric permittivity due to elastic polarization is known, , to be given by the following expression where T is the temperature of the system, n is the relaxator concentration, k B is the Boltzmann constant, and ⟨μ 2 ⟩ is the mean value of , where and are dipole moments of a relaxator in states 2 and 1, respectively.…”

Section: Theorymentioning

confidence: 99%

“…Based on this line of reasoning, we can treat the nanocrystal with thermally activated motion as a two-state system that can relax (a "two-level relaxator"). The change in the dielectric permittivity of the system, i.e., the difference between the static dielectric permittivity and the dielectric permittivity due to elastic polarization is known, 51,52 to be given by the following expression…”

Section: Model For the Dielectric Relaxation Scale Effectmentioning

confidence: 99%

Dielectric Relaxation in Nanocrystals: A Scale Effect

et al. 2023

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The study explores a scale effect inherent to the dielectric relaxation in nanocrystals: the dependence of dielectric relaxation parameters on the size of a nanocrystal. We offer a model of the scale effect for the dielectric relaxation caused by thermally activated motion. In this model, a nanocrystal is considered as a physical infinitesimal volume: a region where a local equilibrium exists. We conclude that the thermally activated motion causes the energy fluctuations in a nanocrystal as a whole. A relation between the intensity of these fluctuations and the size of nanocrystals is derived. According to this relation, the intensity of the fluctuations decreases with the decrease of the nanocrystal sizes. Using the relation, a characteristic of a thermally activated motion−the size of the activation zone−can be determined experimentally. We verify the model using experimental data for the complex dielectric permittivity of the composites (silica gel matrix with undecylenic acid nanocrystalline inclusions of various sizes) in the temperature range from −190 to 50 °C at frequencies 5, 10, 20, and 50 kHz. The results of the experiment agree with the predictions of the model.

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“…In the case of rigid constraint of both plate contours, equation (34) must be substituted in (21). As a result, taking into account (57) and the fact that the values of the derivative of the deflection on the contours of the plate are equal to zero, obtain a linear system of eight algebraic equations.…”

mentioning

confidence: 99%

“…An increase in the stiffness coefficient of the soil leads to a decrease in displacements in magnitude, but the shape of the curves remains, as opposed to a solid plate. This is due to the high rigidity of the circular plate itself, both boundary contours of which are clamped [17][18][19][20][21]. Figure 3 shows the change in radial σr -1 and circumferential σφ -2 stresses along the thickness of the plate on its outer -a and inner -b contours.…”

mentioning

confidence: 99%

Bending of an Elastic Three-Layer Plate With a Hole Connected to the Soil Foundation

Старовойтов¹,

Журавков²,

Pronina³

2021

News of NAN RK. SGTS

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The relevance of this paper is explained by a demand for the development of mechanical and mathematical models and methods for calculating the stress-strain state of the sandwich structural elements. The statement of the boundary value problem on the deformation of a circular sandwich plate with a central hole, connected to the soil foundation, was given. To describe the kinematics of an asymmetric plate pack, the broken line hypotheses are accepted. In a relatively thick lightweight core, the normal does not change its length, remains rectilinear, but rotates through some additional angle. Tuff, coarse grained soil, granite, and gneiss are accepted as the soil foundation. The bearing reaction is described by the Winkler model. The system of equilibrium equations is obtained by the variational method. Its solution is written in displacements through Kelvin functions. A numerical parametric analysis of displacements and stresses in the plate is carried out, their dependence on the type of soil foundation is shown.

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Nature of Dielectric Relaxation in Microcrystalline Cellulose

Cited by 16 publications

References 12 publications

Configuration Transformations in Polyvinyl Chloride–Methylene Blue Composites

Configuration Transformations in Polyvinyl Chloride–Methylene Blue Composites

Dielectric Relaxation in Nanocrystals: A Scale Effect

Bending of an Elastic Three-Layer Plate With a Hole Connected to the Soil Foundation

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